This invention relates to complex shaped structures and more particularly it relates to three dimensional braided structures of a structural composite material.
Fiber-reinforced plastic structures have been used for many years with increasing success because of their high strength, light weight and ease of fabrication compared to the wood or metal structures which they replace. Fibers such as glass, carbon, ceramic and aramid are popular as reinforcement, and thermosetting as well as thermoplastic resins are common polymeric matrices.
Polymeric materials reinforced with continuous filaments are used as precursors for highly-stressed parts such as aerospace components requiring the highest possible strength and stiffness with the lowest possible weight. Non-uniformity of such parts requires that the parts be over-constructed so that the weakest will surpass the service requirements. Integral manufacture of complex structures could improve uniformity of the reinforcing material and reliability of the composite part made from such structures.
Braiding with axial yarns is one process for producing such structures and generally comprises forming an array of axial yarns extending substantially parallel to the axis of the structure and interlacing braiding yarns in a pattern through the array so they are interlaced with one another and with the axial yarns. Known processes for doing this, such as described in European patent publication No. 0113196, do not lend themselves to forming complex shaped structures at relatively high processing speeds and it would be highly desirable to do so.